I can feel your pain. This is going to be the second Father's Day without my dad being here. He was a lifelong hunter and enjoyed everything associated with it. As his Parkinson's progressed he could no longer take to the field as he would have liked, nor keep his beloved hunting dog pack but still went on the odd occasion with us, resting frequently and we would carry his backpack and gear for him.
As I live outside the US where gun ownership is seen as a privilege and not a right we were both fortunate to own firearms [shotguns only] and not only did we enjoy the time together but alot of valuable experience was passed, not to mention that near sacred father to son bonding.
There is something superlatively wonderful about the hunting and shooting sports and especially so within the context of that father and son tradition, my grandfather also having been a hunter and shooter [but he passed away while I was yet a child]. I have his hunting paraphernalia, as both a memory and a souvenir. I was thus more fortunate than you in having him around and having something to remind me always of him. Having said that, you will forgive me for saying that to a certain extent at least you were spared the pain of watching a once vigorous, strong proud man deteriorate.
I went back out to the field afterwards with mixed feelings but knowing that he would have wanted it so. I think it's safe to say your father would have been the same!
Happy Fathers' Day to all dads and others who fulfil such a role, at the TFL Forum. And remember to take your son or daughter hunting and shooting. You might be surprised at the rich dividends it can pay to all parties.